1. Field of the Invention
This invention relates to apparatus for applying labels to a moving surface which may be the surface of an item being fed along a conveyer or the surface of a traveling web, the apparatus providing for high-speed, precise label placement at a desired position on the moving surface.
2. Description of the Prior Art
The demand for accurate and high-speed labeling machines has increased due to the development of labeling schemes such as that described in U.S. Pat. No. 4,183,779, wherein a series of high-speed labelers are required to accurately position color-coded die cut labels in order to consecutively number a series of file folders. When used in such applications, the limitations of existing automatic labeling machines have become apparent. Such existing labelers dispense self-adhesive die cut labels mounted on a carrier web or liner which is drawn from a supply reel and passed sharply around the smooth end of a peeling surface or splitter tongue which causes the labels to separate from the liner. The liner is then drawn backwards by a take-up which is typically a capstan and pressure roller which grip the web therebetween. Rotation of the capstan effects feed of the labels which move forwardly of the peeling surface while the liner is delivered to a take-up reel.
The capstan is normally driven through a friction clutch mechanism used in conjunction with a driving motor. The capstan is started and stopped for each label dispensed or article labeled. The motion of the capstan is necessarily a nearly instantaneous start/stop operation within the mechanical limitations of the driving mechanism employed. The sudden, intermittent motion of the mechanism translates into limited labeler life and may result in breakage of the liner, particularly if the inertia of the tape supply is high.
U.S. Pat. No. 4,294,644 has attempted to overcome these problems by providing a labeler mechanism which gradually accelerates the label to the speed of the item to be labeled and gradually decelerates a subsequent label to a predetermined position. Gradual acceleration and deceleration of the liner and labels has resulted in increased accuracy, extended labeler life and the practical elimination of liner breakage. However, these advantages have been achieved at the expense of increased cost and reduced reliability because of the complexity of the control system which must be employed.
It is desirable, therefore, to provide a labeler mechanism which is relatively less complex in construction and yet will produce the positional accuracy achieved by the aforementioned labeler mechanism. Increased speed of label application is a continuing goal.
In addition, it would be desirable to produce a labeling mechanism which could utilize a continuous length of labeling material attached to the liner rather than the discrete, die cut labels of the prior art. A continuous label construction would reduce costs, eliminate the possibility of lost or misaligned labels and permit greater control over label stock, thus reducing the possibility of misappropriated labels beein applied to unauthorized goods. The aforementioned U.S. Pat. No. 4,294,644 is not capable of utilizing label stock consisting of continuous labeling material affixed to a liner.